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Publication numberUS7706748 B2
Publication typeGrant
Application numberUS 11/167,010
Publication dateApr 27, 2010
Filing dateJun 24, 2005
Priority dateJun 25, 2004
Fee statusPaid
Also published asUS20050288011, WO2006012348A2, WO2006012348A3
Publication number11167010, 167010, US 7706748 B2, US 7706748B2, US-B2-7706748, US7706748 B2, US7706748B2
InventorsSantanu Dutta
Original AssigneeAtc Technologies, Llc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Methods of ground based beamforming and on-board frequency translation and related systems
US 7706748 B2
Abstract
Methods are provided to operate a communications system including a satellite and a satellite gateway. In particular, a feeder link may be provided between the satellite and the satellite gateway over a feeder link frequency band for communication of information between the satellite gateway and the satellite. A service link may be provided between the satellite and at least one radioterminal in a coverage area of the satellite over a service link frequency band. Moreover, the feeder link and service link frequency bands may be different. In addition, a frequency segment of the feeder link may be linearly translated from the feeder link frequency band to the service link frequency band to provide a frequency segment of the service link. Related satellites are also discussed.
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Claims(48)
1. A method of operating a communications system including a satellite and a satellite gateway, the method comprising:
providing a feeder link between the satellite and the satellite gateway, wherein the feeder link is provided over a feeder link frequency band for communication of information between the satellite gateway and the satellite, wherein the feeder link comprises a frequency segment including at least first and second bands of frequencies that provide information between the satellite gateway and the satellite and wherein the first and second bands of frequencies are non-contiguous and separated by a third band of frequencies that does not provide any information between the satellite gateway and the satellite;
providing a service link between the satellite and at least one radioterminal in a coverage area of the satellite, wherein the service link is provided over a service link frequency band and wherein the feeder link and service link frequency bands are different and non-overlapping; and
linearly frequency translating the frequency segment of the feeder link including the first, second, and third bands from the feeder link frequency band to the service link frequency band to provide a frequency segment of the service link including fourth and fifth bands of frequencies including the information provided by the respective first and second bands of frequencies, wherein the fourth and fifth bands of frequencies are non-contiguous and separated by a sixth band of frequencies corresponding to the third band of frequencies that does not provide any information.
2. A method according to claim 1 wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, wherein the frequency segment of the feeder link comprises a first frequency segment of the feeder link, wherein the feeder link comprises a second frequency segment including at least a seventh band of frequencies that provide information between the satellite gateway and the satellite, wherein the first and second frequency segments of the feeder link are non-overlapping, and wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, the method further comprising:
providing a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link is provided over the service link frequency band; and
linearly frequency translating the second frequency segment of the feeder link including the seventh band of frequencies from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the eighth band of frequencies overlaps a portion of the sixth band of frequencies.
3. A method according to claim 2 wherein the first frequency segment of the feeder link comprises a first continuous frequency segment of the feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content for a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the feeder link comprises a second continuous frequency segment of the feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content for a second plurality of radiotermninals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
4. A method according to claim 2 wherein the first frequency segment of the feeder link is transmitted to the satellite using a first polarization and wherein the second frequency segment of the feeder link is transmitted to the satellite using a second polarization, wherein the first and second polarizations are different.
5. A method according to claim 4 wherein the second polarization is orthogonal with respect to the first polarization.
6. A method according to claim 1 wherein a bandwidth of frequencies spanned by the frequency segment of the feeder link is about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.
7. A method according to claim 1 wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, wherein the feeder link comprises a first feeder link, and wherein the frequency segment of the first feeder link comprises a first frequency segment of the first feeder link, the method further comprising:
providing a second feeder link between the satellite and a second satellite gateway, wherein the second feeder link is provided over the feeder link frequency band for communication of information between the second satellite gateway and the satellite, wherein the second frequency segment of the second feeder link includes at least a seventh band of frequencies that provide information between the second satellite gateway and the satellite, and wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies;
providing a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link is provided over the service link frequency band; and
linearly frequency translating the second frequency segment of the second feeder link including the seventh band of frequencies from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the eighth band of frequencies overlaps a portion of the sixth band of frequencies.
8. A method according to claim 7 wherein the first frequency segment of the first feeder link comprises a first continuous frequency segment of the first feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment that provides content for a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the second feeder link comprises a second continuous frequency segment of the second feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment that provides content for a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
9. A method according to claim 7 further comprising:
transmitting first pilot signals from the first satellite gateway to the satellite over the first feeder link;
transmitting second pilot signals from the second satellite gateway to the satellite over the second feeder link wherein the first and second pilot signals are different; and
performing interference cancellation at the satellite based on a priori knowledge of the first and second pilot signals.
10. A method according to claim 1 wherein the frequency segment of the service link provides content for the at least one radioterminal.
11. A method according to claim 1 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area.
12. A method of operating a communications system including a satellite and a satellite gateway, the method comprising:
providing a feeder link between the satellite and the satellite gateway, wherein the feeder link is provided over a feeder link frequency band for communication of information between the satellite gateway and the satellite;
providing a service link between the satellite and at least one radioterminal in a coverage area of the satellite, wherein the service link is provided over a service link frequency band and wherein the feeder link and service link frequency bands are different and non-overlapping, wherein the service link comprises a frequency segment including at least first and second bands of frequencies that provide information between the satellite and the at least one radioterminal and wherein the first and second bands of frequencies are non-contiguous and separated by a third band of frequencies that does not provide any information between the satellite and the at least one radioterminal; and
linearly frequency translating the frequency segment of the service link including the first, second, and third bands from the service link frequency band to the feeder link frequency band to provide a frequency segment of the feeder link including fourth and fifth bands of frequencies including the information provided by the respective first and second bands of frequencies, wherein the fourth and fifth bands of frequencies are non-contiguous and separated by a sixth band of frequencies corresponding to the third band of frequencies that does not provide any information.
13. A method according to claim 12 wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, and wherein the frequency segment of the feeder link comprises a first frequency segment of the feeder link, the method further comprising:
providing a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link is provided over the service link frequency band wherein the second service link comprises a second frequency segment of the second service link including at least a seventh band of frequencies that provide information between the at least one mobile terminal in the second coverage area and the satellite, and wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, and wherein the seventh band of frequencies overlaps a portion of the third band of frequencies; and
linearly frequency translating the second frequency segment of the second service link including the seventh band of frequencies from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the feeder link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the first and second frequency segments of the feeder link are non-overlapping.
14. A method according to claim 13 wherein the first frequency segment of the feeder link comprises a first continuous frequency segment of the feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content from a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the feeder link comprises a second continuous frequency segment of the feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content from a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
15. A method according to claim 13 wherein the first frequency segment of the feeder link is transmitted from the satellite using a first polarization and wherein the second frequency segment of the feeder link is transmitted from the satellite using a second polarization, wherein the first and second polarizations are different.
16. A method according to claim 15 wherein the second polarization is orthogonal with respect to the first polarization.
17. A method according to claim 12 wherein a bandwidth of frequencies spanned by the frequency segment of the feeder link is about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.
18. A method according to claim 12 wherein the service link comprises a first service link, wherein the feeder link comprises a first feeder link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, and wherein the frequency segment of feeder link comprises a first frequency segment of the first feeder link, the method further comprising:
providing a second feeder link between the satellite and a second satellite gateway, wherein the second feeder link is provided over the feeder link frequency band for communication of information between the second satellite gateway and the satellite;
providing a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link is provided over the service link frequency band, wherein the second service link comprises a second frequency segment of the second service link including at least a seventh band of frequencies that provide information between the at least one mobile terminal in the second coverage area and the satellite, wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, and wherein the seventh band of frequencies overlaps a portion of the third band of frequencies; and
linearly frequency translating the second frequency segment of the second service link including the seventh band of frequencies from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the second feeder link including an eighth band of frequencies including the information provided by the seventh band of frequencies.
19. A method according to claim 18 wherein the first frequency segment of the first feeder link comprises a first continuous frequency segment of the first feeder link, wherein the first frequency segment from the first service link comprises a first continuous frequency segment of the first service link that provides content from a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the second feeder link comprises a second continuous frequency segment of the second feeder link, and wherein the second frequency segment from the second service link comprises a second continuous frequency segment of the second service link that provides content from a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
20. A method according to claim 18 further comprising:
transmitting first pilot signals from the satellite over the first feeder link to the first satellite gateway;
transmitting second pilot signals from the satellite over the second feeder link to the second satellite gateway wherein the first and second pilot signals are different; and
performing interference cancellation at the first and second satellite gateways based on a priori knowledge of the first and second pilot signals.
21. A method according to claim 12 wherein the frequency segment of the service link provides content from the at least one radioterminal in the coverage area of the service link.
22. A method according to claim 12 wherein the frequency segment of the service link provides content from a plurality of radioterminals in the coverage area of the service link.
23. A satellite for relaying communications between a satellite gateway and at least one radioterminal in a coverage area of the satellite, the satellite comprising;
a feeder link receiver configured to receive information from the satellite gateway using a feeder link provided over a feeder link frequency band, wherein the feeder link comprises a frequency segment including at least first and second bands of frequencies that provide information between the satellite gateway and the satellite and wherein the first and second bands of frequencies are non-contiguous and separated by a third band of frequencies that does not provide any information between the satellite gateway and the satellite;
a service link transmitter configured to transmit information to the at least one radioterminal in the coverage area using a service link provided over a service link frequency band, wherein the service link frequency band and the feeder link frequency band are different and non-overlapping; and
a frequency translator coupled between the feeder link receiver and the service link transmitter, wherein the frequency translator is configured to provide linear frequency translation of the frequency segment of the feeder link including the first, second, and third bands from the feeder link frequency band to the service link frequency band to provide a frequency segment of the service link including fourth and fifth bands of frequencies including the information provided by the respective first and second bands of frequencies, wherein the fourth and fifth bands of frequencies are non-contiguous and separated by a sixth band of frequencies corresponding to the third band of frequencies that does not provide any information.
24. A satellite according to claim 23 wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, wherein the frequency segment of the feeder link comprises a first frequency segment of the feeder link, wherein the feeder link comprises a second frequency segment including at least a seventh band of frequencies that provide information between the satellite gateway and the satellite, wherein the first and second frequency segments of the feeder link are non-overlapping, wherein the bandwidth of the seventh band of frequencies is no greater that a bandwidth of the third band of frequencies, and wherein the service link transmitter is further configured to transmit information to at least one radioterminal in a second coverage area different than the first coverage area using a second service link provided over the service link frequency band, the satellite further comprising:
a second frequency translator coupled between the feeder link receiver and the service link transmitter, wherein the second frequency translator is configured to provide linear frequency translation of the second frequency segment of the feeder link from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the eighth band of frequencies overlaps a portion of the sixth band of frequencies.
25. A satellite according to claim 24 wherein the first frequency segment of the feeder link comprises a first continuous frequency segment of the feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content for a first plurality of radiotermninals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the feeder link comprises a second continuous frequency segment of the feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content for a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
26. A satellite according to claim 24 wherein the feeder link receiver is configured to receive first frequency segment using a first polarization and to receive the second frequency segment using a second polarization, wherein the first and second polarizations are different.
27. A satellite according to claim 26 wherein the second polarization is orthogonal with respect to the first polarization.
28. A satellite according to claim 23 wherein a bandwidth of frequencies spanned by the frequency segment of the feeder link is about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.
29. A satellite according to claim 23 wherein the feeder link receiver comprises a first feeder link receiver, wherein the frequency translator comprises a first frequency translator, wherein the feeder link comprises a first feeder link, wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, and wherein the frequency segment of the feeder link comprises a first frequency segment of the first feeder link, the satellite further comprising:
a second feeder link receiver configured to receive information from a second satellite gateway using a second feeder link provided over the feeder link frequency band, wherein the second frequency segment of the second feeder link includes at least a seventh band of frequencies that provide information between the second satellite gateway and the satellite, and wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, wherein the service link transmitter is configured to provide a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link is provided over the service link frequency band; and
a second frequency translator coupled between the second feeder link receiver and the service link transmitter, wherein the second frequency translator is configured to provide linear frequency translation of the second frequency segment of the second feeder link including the seventh band of frequencies from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the eighth band of frequencies overlaps a portion of the sixth band of frequencies.
30. A satellite according to claim 29 wherein the first frequency segment of the first feeder link comprises a first continuous frequency segment of the first feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content for a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the second feeder link comprises a second continuous frequency segment of the second feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content for a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
31. A satellite according to claim 29 wherein the first feeder link receiver is configured to receive first pilot signals from the first satellite gateway over the first feeder link, wherein the second feeder link receiver is configured to receive second pilot signals from the second satellite gateway over the second feeder link, wherein the first and second pilot signals are different, and wherein the first and/or second feeder link receivers are configured to perform interference cancellation based on a priori knowledge of the first and second pilot signals.
32. A satellite according to claim 23 wherein the frequency segment of the service link provides content for the at least one radioterminal in the coverage area.
33. A satellite according to claim 23 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area.
34. A satellite for relaying communications between a satellite gateway and at least one radioterminal in a coverage area of the satellite, the satellite comprising:
a service link receiver configured to receive information from the at least one radioterminal in the coverage area using a service link provided over a service link frequency band, wherein the service link comprises a frequency segment including at least first and second bands of frequencies that provide information between the satellite and the at least one radioterminal and wherein the first and second bands of frequencies are non-contiguous and separated by a third band of frequencies that does not provide any information between the satellite and the at least one radioterminal;
a feeder link transmitter configured to transmit information to the satellite gateway using a feeder link provided over a feeder link frequency band, wherein the service link frequency band and the feeder link frequency band are different and non-overlapping; and
a frequency translator coupled between the service link receiver and the feeder link transmitter, wherein the frequency translator is configured to provide linear frequency translation of the frequency segment of the service link including the first, second, and third bands from the service link frequency band to the feeder link frequency band to provide a frequency segment of the feeder link including fourth and fifth bands of frequencies including the information provided by the respective first and second bands of frequencies, wherein the fourth and fifth bands of frequencies are non-contiguous and separated by a sixth band of frequencies corresponding to the third band of frequencies that does not provide any information.
35. A satellite according to claim 34 wherein the frequency translator comprises a first frequency translator, wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, and wherein the frequency segment of the feeder link comprises a first frequency segment of the feeder link, wherein the service link receiver is further configured to receive information from at least one radioterminal in a second coverage area different than the first coverage area using a second service link provided over the service link frequency band, wherein the second service link comprises a second frequency segment of the second service link including at least a seventh band of frequencies that provide information between the at least one mobile terminal in the second coverage area and the satellite, wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, and wherein the seventh band of frequencies overlaps a portion of the third band of frequencies, the satellite further comprising:
a second frequency translator coupled between the service link receiver and the feeder link transmitter, wherein the second frequency translator is configured to provide linear frequency translation of the second frequency segment of the second service link including the seventh band of frequencies from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the feeder link including an eighth band of frequencies including the information provided by the seventh band of frequencies, and wherein the first and second frequency segments of the feeder link are non-overlapping.
36. A satellite according to claim 35 wherein the first frequency segment of the feeder link comprises a first continuous frequency segment of the feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content from a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the feeder link comprises a second continuous frequency segment of the feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content from a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
37. A satellite according to claim 35 wherein the feeder link transmitter is configured to transmit the first frequency segment using a first polarization and to transmit the second frequency segment using a second polarization, wherein the first and second polarizations are different.
38. A satellite according to claim 37 wherein the second polarization is orthogonal with respect to the first polarization.
39. A satellite according to claim 34 wherein a bandwidth of frequencies spanned by the frequency segment of the feeder link is about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.
40. A satellite according to claim 34 wherein the feeder link transmitter comprises a first feeder link transmitter, wherein the feeder link comprises a first feeder link, wherein the service link comprises a first service link, wherein the frequency segment of the service link comprises a first frequency segment of the first service link, and wherein the frequency segment of the feeder link comprises a first frequency segment of the first feeder link, the satellite further comprising:
a second feeder link transmitter configured to transmit information to a second satellite gateway using a second feeder link provided over the feeder link frequency band, wherein the service link receiver is configured to provide a second service link between the satellite and at least one radioterminal in a second coverage area of the satellite different than the first coverage area, wherein the second service link comprises a second frequency segment of the second service link including at least a seventh band of frequencies that provide information between the at least one mobile terminal in the second coverage area and the satellite, wherein a bandwidth of the seventh band of frequencies is no greater than a bandwidth of the third band of frequencies, and wherein the seventh band of frequencies overlaps a portion of the third band of frequencies; and
a second frequency translator coupled between the second feeder link receiver and the service link transmitter, wherein the second frequency translator is configured to provide linear frequency translation of the second frequency segment of the second service link including the seventh band of frequencies from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the second feeder link including an eighth band of frequencies including the information provided by the seventh band of frequencies.
41. A satellite according to claim 40 wherein the first frequency segment of the first feeder link comprises a first continuous frequency segment of the first feeder link, wherein the first frequency segment of the first service link comprises a first continuous frequency segment of the first service link that provides content from a first plurality of radioterminals in the first coverage area using different frequencies separated over the first continuous frequency segment of the first service link, wherein the second frequency segment of the feeder link comprises a second continuous frequency segment of the feeder link, and wherein the second frequency segment of the second service link comprises a second continuous frequency segment of the second service link that provides content from a second plurality of radioterminals in the second coverage area using different frequencies separated over the second continuous frequency segment of the second service link.
42. A satellite according to claim 40 wherein the first feeder link transmitter is configured to transmit first pilot signals to the first satellite gateway over the first feeder link, wherein the second feeder link transmitter is configured to transmit second pilot signals to the second satellite gateway over the second feeder link, wherein the first and second pilot signals are different, and wherein the first and/or second satellite gateways are configured to perform interference cancellation based on a priori knowledge of the first and second pilot signals.
43. A satellite according to claim 34 wherein the frequency segment of the service link provides content from the at least one radioterminal in the coverage area.
44. A satellite according to claim 34 wherein the frequency segment of the service link provides content from a plurality of radioterminals in the coverage area.
45. A method according to claim 1 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area using different frequencies separated over the frequency segment of the service link, and wherein linearly frequency translating comprises linearly frequency translating the frequency segment of the feeder link including the first, second, and third bands from the feeder link frequency band to the service link frequency band to provide the frequency segment of the service link including the different frequencies separated over the frequency segment of the service link that provides content for the plurality of radiotelephones.
46. A method according to claim 12 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area using different frequencies separated over the frequency segment of the service link, and wherein linearly frequency translating comprises linearly frequency translating the frequency segment of the service link that provides content from the plurality of radiotelephones from the service link frequency band including the different frequencies separated over the frequency segment of the service link to the feeder link frequency band to provide the frequency segment of the feeder link including the first, second, and third bands.
47. A satellite according to claim 23 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area using different frequencies separated over the frequency segment of the service link, and wherein the frequency translator is configured to linearly frequency translate the frequency segment of the feeder link including the first, second, and third bands from the feeder link frequency band to the service link frequency band to provide the frequency segment of the service link including the different frequencies separated over the frequency segment of the service link that provides content for the plurality of radiotelephones.
48. A satellite according to claim 34 wherein the frequency segment of the service link provides content for a plurality of radioterminals in the coverage area using different frequencies separated over the frequency segment of the service link, and wherein the frequency translator is configured to linearly frequency translate the frequency segment of the service link including the different frequencies separated over the frequency segment of the service link that provides content from the plurality of radiotelephones from the service link frequency band to the feeder link frequency band including the first, second, and third bands to provide the frequency segment of the feeder link.
Description
RELATED APPLICATION

The present application claims the benefit of priority from U.S. Provisional Application No. 60/583,218 filed Jun. 25, 2004, and entitled “Methods Of Ground Based Beamforming And On-Board Frequency Translation And Related Systems.” The disclosure of the above referenced U.S. provision application is hereby incorporated herein in its entirety by reference.

FIELD OF THE INVENTION

This invention relates to wireless communications systems and methods, and more particularly to satellite communications systems and methods.

BACKGROUND

Satellite radiotelephone communications systems and methods are widely used for radiotelephone communications. Satellite radiotelephone communications systems and methods generally employ at least one space-based component, such as one or more satellites that are configured to wirelessly communicate with a plurality of satellite radiotelephones.

A satellite radiotelephone communications system or method may utilize a single antenna beam covering an entire area served by the system. Alternatively, in cellular satellite radiotelephone communications systems and methods, multiple beams are provided, each of which can serve distinct geographical areas in the overall service region, to collectively serve an overall satellite footprint. Thus, a cellular architecture similar to that used in conventional terrestrial cellular radiotelephone systems and methods can be implemented in cellular satellite-based systems and methods. The satellite typically communicates with radiotelephones over a bidirectional communications pathway, with radiotelephone communication signals being communicated from the satellite to the radiotelephone over a downlink or forward link, and from the radiotelephone to the satellite over an uplink or return link.

The overall design and operation of cellular satellite radiotelephone systems and methods are well known to those having skill in the art, and need not be described further herein. Moreover, as used herein, the term “radiotelephone” includes cellular and/or satellite radiotelephones with or without a multi-line display; Personal Communications System (PCS) terminals that may combine a radiotelephone with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and a pager, Internet/intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver. Radiotelephones may also be referred to herein as “radioterminals” or simply “terminals”.

As is well known to those having skill in the art, terrestrial networks can enhance cellular satellite radiotelephone system availability, efficiency and/or economic viability by terrestrially reusing at least some of the frequency bands that are allocated to cellular satellite radiotelephone systems. In particular, it is known that it may be difficult for cellular satellite radiotelephone systems to reliably serve densely populated areas, because the satellite signal may be blocked by high-rise structures and/or may not penetrate into buildings. As a result, the satellite spectrum may be underutilized or unutilized in such areas. The use of terrestrial retransmission of at least some of the satellite band frequencies can reduce or eliminate this problem.

Moreover, the capacity of the overall system can be increased significantly by the introduction of terrestrial retransmission, since terrestrial frequency reuse can be much denser than that of a satellite-only system. In fact, capacity can be enhanced where it may be mostly needed, i.e., densely populated urban/industrial/commercial areas. As a result, the overall system can become much more economically viable, as it may be able to serve a much larger subscriber base. Finally, satellite radiotelephones for a satellite radiotelephone system having a terrestrial component within the same satellite frequency band and using substantially the same air interface for both terrestrial and satellite communications can be more cost effective and/or aesthetically appealing. Conventional dual band/dual mode alternatives, such as the well known Thuraya, Iridium and/or Globalstar dual mode satellite/terrestrial radiotelephone systems, may duplicate some components, which may lead to increased cost, size and/or weight of the radiotelephone.

United States Patent Application Publication No. U.S. 2003/0054760 A1, published Mar. 20, 2003, and entitled Systems and Methods for Terrestrial Reuse of Cellular Satellite Frequency Spectrum, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein, describes that a satellite radiotelephone frequency can be reused terrestrially by an ancillary terrestrial network even within the same satellite cell, using interference cancellation techniques. In particular, the satellite radiotelephone system according to some embodiments of published Patent Application 2003/0054760 includes a space-based component that is configured to receive wireless communications from a first radiotelephone in a satellite footprint over a satellite radiotelephone frequency band, and an ancillary terrestrial network that is configured to receive wireless communications from a second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band. The space-based component also receives the wireless communications from the second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band as interference, along with the wireless communications that are received from the first radiotelephone in the satellite footprint over the satellite radiotelephone frequency band. An interference reducer is responsive to the space-based component and to the ancillary terrestrial network that is configured to reduce the interference from the wireless communications that are received by the space-based component from the first radiotelephone in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from the second radiotelephone in the satellite footprint over the satellite radiotelephone frequency band.

United States Patent Application Publication No. 2003/0054761 A1, published Mar. 20, 2003, and entitled Spatial Guardbands for Terrestrial Reuse of Satellite Frequencies, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein, describes satellite radiotelephone systems that include a space-based component that is configured to provide wireless radiotelephone communications in a satellite footprint over a satellite radiotelephone frequency band. The satellite footprint is divided into a plurality of satellite cells, in which satellite radiotelephone frequencies of the satellite radiotelephone frequency band are spatially reused. An ancillary terrestrial network is configured to terrestrially reuse at least one of the ancillary radiotelephone frequencies that is used in a satellite cell in the satellite footprint, outside the cell and in some embodiments separated therefrom by a spatial guardband. The spatial guardband may be sufficiently large to reduce or prevent interference between the at least one of the satellite radiotelephone frequencies that is used in the satellite cell in the satellite footprint, and the at least one of the satellite radiotelephone frequencies that is terrestrially reused outside the satellite cell and separated therefrom by the spatial guardband. The spatial guardband may be about half a radius of a satellite cell in width.

United States Patent Application Publication No. U.S. 2003/0054815 A1, published Mar. 20, 2003, and entitled Methods and Systems for Modifying Satellite Antenna Cell Patterns in Response to Terrestrial Reuse of Satellite Frequencies, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein, describes that space-based wireless radiotelephone communications are provided in a satellite footprint over a satellite radiotelephone frequency band. The satellite footprint is divided into satellite cells in which satellite radiotelephone frequencies of the satellite radiotelephone frequency band are spatially reused. At least one of the satellite radiotelephone frequencies that is assigned to a given satellite cell in the satellite footprint is terrestrially reused outside the given satellite cell. A radiation pattern of at least the given satellite cell is modified to reduce interference with the at least one of the satellite radiotelephone frequencies that is terrestrially reused outside the given satellite cell.

SUMMARY OF THE INVENTION

According to some embodiments of the present invention, methods may be provided to operate a communications system including a satellite and a satellite gateway. In particular, a feeder link may be provided between the satellite and the satellite gateway over a feeder link frequency band for communication of information between the satellite gateway and the satellite. A service link may be provided between the satellite and at least one radioterminal in a coverage area of the satellite over a service link frequency band, and the feeder link and service link frequency bands may be different. In addition, a frequency segment of the feeder link may be linearly translated from the feeder link frequency band to the service link frequency band to provide a frequency segment of the service link. The frequency segment of the service link may provide content for the at least one radioterminal and/or for a plurality of radioterminals in the coverage area.

A second service link may also be provided between the satellite and at least one radioterminal in a second coverage area of the satellite over the service link frequency band. Moreover, a second frequency segment of the feeder link may be linearly translated from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link. The first frequency segment of the first service link may provide content for a first plurality of radioterminals in the first coverage area, and the second frequency segment of the second service link may provide content for a second plurality of radioterminals in the second coverage area. Moreover, the first frequency segment of the feeder link may be transmitted to the satellite using a first polarization, the second frequency segment of the feeder link may be transmitted to the satellite using a second polarization, and the first and second polarizations may be different. More particularly, the second polarization may be orthogonal with respect to the first polarization. In addition, a bandwidth of frequencies spanned by the frequency segment of the feeder link may be about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.

A second feeder link may also be provided between the satellite and a second satellite gateway over the feeder link frequency band for communication of information between the second satellite gateway and the satellite, and a second service link may be provided between the satellite and at least one radioterminal in a second coverage area of the satellite over the service link frequency band. In addition, a frequency segment of the second feeder link may be linearly translated from the feeder link frequency band to the service link frequency band to provide a second frequency segment of the second service link. The first frequency segment of the first service link may provide content for a first plurality of radioterminals in the first coverage area, and the second frequency segment of the second service link may provide content for a second plurality of radioterminals in the second coverage area. Interference between feeder links may be reduced by transmitting first pilot signals from the first satellite gateway to the satellite over the first feeder link, and transmitting second pilot signals from the second satellite gateway to the satellite over the second feeder link with the first and second pilot signals being different. Accordingly, interference cancellation may be performed at the satellite based on a priori knowledge of the first and second pilot signals.

According to additional embodiments of the present invention, methods may be provided to operate a communications system including a satellite and a satellite gateway. In particular, a feeder link may be provided between the satellite and the satellite gateway over a feeder link frequency band for communication of information between the satellite gateway and the satellite. In addition, a service link may be provided between the satellite and at least one radioterminal in a coverage area of the satellite over a service link frequency band, and the feeder link and service link frequency bands may be different. A frequency segment of the service link may be linearly translated from the service link frequency band to the feeder link frequency band to provide a frequency segment of the feeder link.

The frequency segment of the service link may provide content from the at least one radioterminal and/or from a plurality of radioterminals in the coverage area. In addition, a bandwidth of frequencies spanned by the frequency segment of the feeder link may be about the same as a bandwidth of frequencies spanned by the frequency segment of the service link.

A second service link may also be provided between the satellite and at least one radioterminal in a second coverage area of the satellite over the service link frequency band, and a second frequency segment of the second service link may be linearly translated from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the feeder link. Moreover, the first frequency segment of the first service link may provide content from a first plurality of radioterminals in the first coverage area, and the second frequency segment of the second service link may provide content from a second plurality of radioterminals in the second coverage area. In addition, the first frequency segment of the feeder link may transmitted from the satellite using a first polarization, the second frequency segment of the feeder link may be transmitted from the satellite using a second polarization, and the first and second polarizations may be different. More particularly, the second polarization may be orthogonal with respect to the first polarization. The frequency segment of the service link may provide content for the at least one radioterminal and/or for a plurality of radioterminals in the coverage area.

In addition, a second feeder link may be provided between the satellite and a second satellite gateway over the feeder link frequency band for communication of information between the second satellite gateway and the satellite, and a second service link may be provided between the satellite and at least one radioterminal in a second coverage area of the satellite over the service link frequency band. Moreover, a second frequency segment of the second service link may be linearly translated from the service link frequency band to the feeder link frequency band to provide a second frequency segment of the second feeder link. The first frequency segment from the first service link may provide content from a first plurality of radioterminals in the first coverage area, and the second frequency segment from the second service link may provide content from a second plurality of radioterminals in the second coverage area. In addition, first pilot signals may be transmitted from the satellite over the first feeder link to the first satellite gateway, second pilot signals may be transmitted from the satellite over the second feeder link to the second satellite gateway, and the first and second pilot signals may be different. Interference cancellation may thus be performed at the first and second satellite gateways based on a priori knowledge of the first and second pilot signals.

According to still more embodiments of the present invention, a satellite may be provided to relay communications between a satellite gateway and at least one radioterminal in a coverage area of the satellite. The satellite may include a feeder link receiver, a service link transmitter and a frequency translator. The feeder link receiver may be configured to receive information from the satellite gateway using a feeder link provided over a feeder link frequency band. The service link transmitter may be configured to transmit information to the at least one radioterminal in the coverage area using a service link provided over a service link frequency band, and the service link frequency band and the feeder link frequency band may be different. The frequency translator may be coupled between the feeder link receiver and the service link transmitter, and the frequency translator may be configured to provide linear frequency translation of a frequency segment of the feeder link from the feeder link frequency band to the service link frequency band to thereby provide a frequency segment of the service link.

According to yet additional embodiments of the present invention, a satellite may be provided to relay communications between a satellite gateway and at least one radioterminal in a coverage area of the satellite. The satellite may include a service link receiver, a feeder link transmitter, and a frequency translator coupled between the service link receiver and the feeder link transmitter. The service link receiver may be configured to receive information from the at least one radioterminal in the coverage area using a service link provided over a service link frequency band. The feeder link transmitter may be configured to transmit information to the satellite gateway using a feeder link provided over a feeder link frequency band, and the service link frequency band and the feeder link frequency band may be different. The frequency translator may be configured to provide linear frequency translation of a frequency segment of the service link from the service link frequency band to the feeder link frequency band to provide a frequency segment of the feeder link.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a space-based communications network including satellite gateways, at least one satellite, and mobile radioterminals according to embodiments of the present invention.

FIGS. 2 a-c are spectrum occupancy diagrams illustrating transponder frequency translation using arbitrary spectrum mapping.

FIGS. 3 a-c are spectrum occupancy diagrams illustrating transponder frequency translation using linear spectrum mapping.

FIG. 4 is a block diagram illustrating satellites according to embodiments of the present invention.

DETAILED DESCRIPTION

Specific exemplary embodiments of the invention now will be described with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like designations refer to like elements. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It will be understood that although the terms first and second may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first component below could be termed a second component, and similarly, a second component may be termed a first component without departing from the teachings of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The symbol “/” is also used as a shorthand notation for “and/or”.

As shown in FIG. 1, a space-based communications network may include at least one satellite 101 and one or more ground-based satellite gateways 103 a-b providing communications service for mobile radioterminals 105 a-e located in one or more coverage areas 107 a-e of the satellite 101. Communications with a mobile radiotelephone 105 a-e may be provided using a respective service link transmitted over a satellite spot beam for the respective coverage area 107 a-e. Moreover, a service link for a particular mobile radioterminal may be defined to include a service up-link for transmission from the mobile radioterminal to the satellite 101 and a service down-link for transmissions from the satellite 101 to the mobile radioterminal. A satellite spot beam for a respective coverage area may support a plurality of service links for a respective plurality of mobile radioterminals in the coverage area. Different service down-links in a same and/or different spot beam may be separated, for example, by frequency, time, and/or code. Similarly, different service up-links in a same and/or different spot beam may be separated, for example, by frequency (for example, FDM/FDMA and/or OFDM/OFDMA), time (for example, TDM/TDMA), and/or code (for example, CDM/CDMA).

By providing a plurality of antenna elements at the satellite 101, a service link can be directed over a particular spot beam providing service for a mobile radioterminal located in a respective coverage area. When transmitting a service down-link from the satellite for a particular mobile radioterminal, different complex weightings may be applied from the different antenna elements to define the spot beam over which the service down-link is to be transmitted. Accordingly, a frequency reuse pattern may be established for the different spot beams providing service for the different coverage areas so that the same frequencies may not be used for service up-links in adjacent coverage areas and so that the same frequencies may not be used for service down-links in adjacent coverage areas. For example, the same frequencies may not be used for service up-links and down-links in coverage areas 107 a and 107 b. In contrast, one or more of the same frequencies may be used for service up-links and down-links in coverage areas 107 a and 107 c.

Similarly, communications may be transmitted between the satellite 101 and one or more satellite gateways 103 a-b using respective feeder links. Moreover, a feeder link for a particular satellite gateway may be defined to include a feeder up-link for transmissions from the satellite gateway to the satellite(s) and a feeder down-link for transmissions from the satellite(s) to the satellite gateway. Moreover, one or more satellite gateways 103 a-b may be coupled to a conventional communications network such as a public switched wireline and/or wireless telephone network 109.

Accordingly, communications between a mobile radioterminal and the public switched telephone network 109 may be supported by a service link between the mobile ratioterminal and the satellite 101 and by a feeder link between the satellite 101 and a satellite gateway. More particularly, transmissions from the public switched telephone network 109 to the mobile radioterminal 105 a may be provided using a feeder up-link, such as a feeder link of Feeder Link 1 from the satellite gateway 103 a, to the satellite 101 and using a service down-link of Service Link 1 from satellite 101 to mobile radioterminal 105 a over a spot beam for coverage area 107 a. Transmissions from the mobile radioterminal 105 a to the public switched telephone network 109 may be provided using a service up-link of Service Link 1 from the mobile radioterminal 105 a to the satellite 101 over the spot beam providing service for coverage area 107 a, and using a feeder down-link, such as a feeder down-link of Feeder Link 1, from satellite 101 to the satellite gateway 103 a.

The Feeder Link(s) between one or more satellite gateways 103 a-b and the satellite 101 may be provided over a feeder link frequency band(s) (such as a Ku-band feeder link frequency band(s)), the Service Links between one or more mobile radioterminals 105 a-e and the satellite 101 may be provided over a service link frequency band(s) (such as an L-band and/or an S-band service link frequency band(s)), and the feeder link and service link frequency bands may be different. For example, information for a transmission from PSTN 109 to mobile radioterminal 105 a is transmitted on a feeder up-link of Feeder Link 1 in the feeder link frequency band and then transmitted on a service down-link of Service Link 1 in the service link frequency band. Accordingly, the information is mapped from the feeder link frequency band to the service link frequency band. Similarly, information for a transmission from the mobile radioterminal 105 a to the PSTN 109 is transmitted on a service up-link of Service Link 1 in the service link frequency band and then transmitted on a feeder down-link of Feeder Link 1 (and/or Feeder Link 2) in the feeder link frequency band. Accordingly, the information is mapped from the service link frequency band to the feeder link frequency band.

Service link beam forming may be performed either at the satellite 101 and/or at the satellite gateway. For example, in the Thuraya and ACeS geo-stationary satellite systems, service link beam forming is performed at the satellite (Thuraya performs beam forming digitally, while analog beam forming is implemented in ACeS). Also, in the Iridium and Globalstar non-geo-stationary satellite systems, service link beam forming is performed at the satellite(s). In contrast to satellite-based service link beam forming, U.S. Pat. No. 5,903,549 to von der Embse et al. describes a method permitting beam forming at a ground station. The disclosure of U.S. Pat. No. 5,903,549 is hereby incorporated herein by reference in its entirety as if set forth fully herein. Also, U.S. Provisional Application No. 60/572,164 filed May 18, 2004, entitled Space-Based Networks And Methods With Ground-Based Beam Forming describes ground-based and space-based beam forming systems and methods. The above referenced U.S. Provisional Application is assigned to the assignee of the present invention, and the disclosure of the above referenced U.S. Provisional Application is hereby incorporated herein by reference in its entirety as if set forth fully herein. As discussed above, beam forming for a service link is used to define a spot beam over which the service down-link is transmitted from the satellite and over which the service up-link is received at the satellite. For example, the spot beam for a service down-link can be defined by applying different weights (such as different complex weights providing different phase and amplitude information) to the service down-link for each antenna feed element to provide a desired antenna pattern gain and/or phase profile(s) over a spot beam to a satellite coverage area on the ground. When transmitted to the ground, these antenna pattern gain and/or phase profiles may define a spot beam for a satellite coverage area (also referred to as a satellite cell) having a desired size, amplitude roll-off, and/or phase characteristic.

A non-demodulating and/or non-regenerating satellite transponder may perform the following signal processing tasks. First, the satellite transponder may provide frequency translation between the feeder link frequency spectrum and the service link frequency spectrum. Second, the satellite transponder may perform beam forming operations as discussed above. More particularly, the satellite transponder may determine and/or receive from the ground the weights (such as complex weights providing phase and amplitude information) to be applied to each service link for each antenna element to direct the service link over the appropriate spot beam.

According to a particular example illustrated in FIGS. 2 a-c, a first spot beam (Beam 1) transmitted from a satellite to a first satellite coverage area may include service links to be transmitted over the service link frequency spectrum as illustrated in FIG. 2 a, and a second spot beam (Beam 2) transmitted from the satellite to a second satellite coverage area may include service links to be transmitted over the service link frequency spectrum as illustrated in FIG. 2 b. In the example of FIGS. 2 a-c, Beam 1 and Beam 2 may provide service for non-adjacent satellite coverage areas to reduce interference between service links using overlapping portions of the service link frequency band (spectrum). Moreover, occupancy of the service link frequency band by service links of either Beam 1 or Beam 2 may be non-contiguous as shown in FIGS. 2 a and 2 b.

The information for the service links of Beams 1 and 2 may be communicated between a satellite gateway and the satellite over a feeder link using a feeder link frequency band different than the service link frequency band used for Beams 1 and 2. As shown in FIG. 2 c, portions of the service link frequency band occupied by service links of Beams 1 and 2 may be translated (or mapped) to/from the feeder link frequency band in a manner so that an occupied portion of the feeder link frequency band is compacted. Frequency translation (mapping) as illustrated in FIGS. 2 a-c, may be referred to as non-linear mapping and/or arbitrary mapping.

By compacting the information transmitted over the feeder link, an efficiency of usage of the feeder link frequency band can be improved. Compacting, however, may require the use of a relatively large number of frequency translators. For example, a different frequency translator may be used for each block of the service link frequency band of each spot beam being translated to/from the feeder link frequency band with a different frequency shift. In the example of FIGS. 2 a-c, seven frequency translators may be used at the satellite to accomplish the illustrated translations. Each frequency translator may be provided by one or more digital signal processors performing digital filtering using fast Fourier transforms (FFT) and/or inverse fast Fourier transforms (IFFT). Accordingly, a digital signal processing (DSP) module may be used to perform beam forming and/or frequency translation functions.

While a digital signal processor in a satellite transponder may provide flexibility in frequency translation and/or beam forming, a digital signal processing module for a satellite may be one of the most complex items in a satellite payload. Moreover, increasingly complex digital signal processing modules in satellites may significantly increase power consumption, payload mass, reliability, and/or satellite cost, and increasingly complex digital signal processing modules may also lengthen schedules to build and/or deploy a satellite. Accordingly, advantages may be provided by reducing a complexity of and/or eliminating a digital signal processing module in a satellite by moving signal processing functions to one or more ground based satellite gateways.

In particular, a linear frequency translation (mapping) of information between the feeder link frequency band and the service link frequency band can be used to reduce a complexity of processing performed at the satellite 101, and the beam forming may be performed at the satellite gateway(s) 103 a and/or 103 b. More particularly, the feeder link frequency band may be divided into segments, with each segment of the feeder link frequency band corresponding to a respective spot beam and/or satellite antenna feed element. Accordingly, two frequency translators may be provided at the satellite 101 for each spot beam and/or satellite antenna feed element, with a first frequency translator being used to translate a segment of the feeder up-link frequency band to a segment of the service down-link frequency band for the spot beam and/or satellite antenna feed element, and with a second frequency translator being used to translate a segment of the service up-link frequency band for the spot beam and/or satellite antenna feed element to a segment of the feeder down-link frequency band. A third frequency translator may be used to translate a segment of the service up-link frequency band for the spot beam and/or satellite antenna feed element to a segment of the feeder down-link frequency band if the satellite receive antenna subsystem is configured to receive more than one spatial polarization (i.e., Right-Hand Circular Polarization (RHCP) and Left-Hand Circular Polarization (LHCP)).

Systems and methods for reducing satellite feeder link bandwidth/carriers in cellular satellite systems are discussed in U.S. Patent Application No. 60/383,688 to Karabinis filed May 28, 2002, and assigned to the assignee of the present invention. The disclosure of U.S. Patent Application No. 60/383,688 is incorporated herein in its entirety by reference. As discussed in U.S. Patent Application No. 60/383,688, information content is nonidentically mapped between service link carriers and feeder link carriers at a cellular satellite. A reduced number of satellite feeder link carriers compared to the number of satellite service link carriers and/or a reduced total bandwidth of the satellite feeder link carriers compared to the satellite service link carriers thereby may be obtained.

In the example of FIGS. 3 a-c, a linear frequency translation between feeder and service links is used to support beams 1 and 2 illustrated in FIGS. 3 a and 3 b with the beams 1 and 2 of FIGS. 3 a and 3 b being the same as beams 1 and 2 of FIGS. 2 a and 2 b discussed above. More particularly, two frequency translators (one for Beam 1 and one for Beam 2) may be used to perform the illustrated translation for service down-links for coverage areas 107 a and 107 c (including down-links for Service Link 1 and Service Link 4, respectively). More particularly, a first segment (Segment 1) of the feeder link frequency band may be used to transmit information (from a satellite gateway, such as satellite gateway 103 a and/or 103 b, to the satellite 101) for service down-links of Beam 1 corresponding to coverage area 107 a, and a second segment (Segment 2) of the feeder link frequency band may be used to transmit information (from a satellite gateway, such as satellite gateway 103 a and/or 103 b, to the satellite 101) for service down-links of Beam 2 corresponding to coverage area 107 c. As discussed above, the feeder link frequency band used for communications between the satellite 101 and the satellite gateway(s) 103 a and/or 103 b does not overlap with the service link frequency band used for communications between the satellite 101 and the mobile radioterminals 105.

At the satellite 101, the first segment (Segment 1) of the feeder link frequency band transmitted by at least one satellite gateway (such as satellite gateway 103 a and/or 103 b) illustrated in FIG. 3 c is translated (mapped) to a segment of the service link frequency band allocated for service down-links to coverage area 107 a over Beam 1 as shown in FIG. 3 a. The satellite 101 can then apply appropriate (generally complex) antenna element weights so that service down-links are transmitted over the desired spot beam (Beam 1) providing service for the coverage area 107 a. Similarly, the second segment (Segment 2) of the feeder link frequency band that is transmitted by at least one satellite gateway (such as satellite gateway 103 a and/or 103 b) illustrated in FIG. 3 c is translated (mapped) to a segment of the service link frequency band allocated for service down-links to coverage area 107 c over Beam 2 as shown in FIG. 3 b. The satellite 101 can then apply appropriate antenna element weights to the translated (mapped) feeder-link band frequency band segment so that service down-links are transmitted over the desired spot beam (Beam 2) providing service for the coverage area 107 c. It will be understood that the appropriate antenna element weights may be applied to the feeder-link band frequency segment before it is translated (mapped) from the feeder link band to the service link band. It will also be understood that the appropriate antenna element weights may be applied at the satellite and/or at the satellite gateway(s).

Frequency allocation and translation (mapping) as discussed above with respect to FIGS. 3 a-c, may thus allow a reduced complexity of satellite operation and/or payload. A greater bandwidth of feeder link frequency spectrum, however, may be consumed. According to embodiments of the present invention, a two dimensional feeder link frequency spectrum may be provided to increase feeder link capacity. For example, an effective feeder link bandwidth may be doubled by providing two orthogonally polarized feeder links between a satellite gateway, such as satellite gateway 103 a, and the satellite 101 using the same feeder link frequency spectrum. In an alternative, the two orthogonally polarized feeder links may be provided between the satellite 101 and respective (adjacent or spaced apart) satellite gateways 103 a-b.

In addition or in an alternative, cellular frequency reuse may be used for feeder links between the satellite and a plurality of spaced apart satellite gateways. For example, the satellite 101 may include directional feeder link antennas each directed to a respective satellite gateway, and the feeder link frequency band, in its entirety and/or partially, may be allocated to the different satellite gateways to reduce interference therebetween. In other words, different feeder link spot beams may be provided so that adjacent feeder link spot beams do not share same portions of the feeder link frequency band. Same portions of the feeder link frequency band may be shared by spaced apart feeder link spot beams.

When providing cellular frequency reuse for feeder links, sufficient isolation may need to be provided between feeder link cells (spot beams) to maintain a sufficient ratio of C/(NO+IO) in the feeder link budget where C is the carrier power, NO is the noise spectral density, and IO is the interference spectral density. Providing sufficient isolation between feeder link spot beams (cells) may require a relatively large feeder link antenna aperture at the satellite 101. Apertures of feeder link antennas at the satellite 101 may be reduced by including a pilot signal and/or a data sequence (that may be a priori known to a gateway receiver) in feeder down-links from the satellite 101 to the satellite gateways 103 a-b, and interference cancellation may be performed among the satellite gateways based on a priori knowledge of the pilot and/or data sequence waveform.

In addition, a terrestrial communications network including one or a plurality of terrestrial base stations may provide communications for radioterminals in one or more of the satellite coverage areas 107 a-e using frequencies of the satellite service link frequency band. For example, a terrestrial communications network may provide communications service for mobile radioterminals in an urban area of a satellite coverage area to provide a higher density of communications than may be desirable for satellite communications. Communications services for the same mobile radioterminals may be provided by the satellite in regions (such as rural regions) of the satellite coverage area(s) not covered by a terrestrial communications network.

The sharing of frequencies of a satellite frequency band between a space-based communications network and a terrestrial communications network is discussed, for example, in the following U.S. patents and U.S. patent publications. Satellite radioterminal communications systems and methods that may employ terrestrial reuse of satellite frequencies are described, for example, in U.S. Pat. No. 6,684,057 to Karabinis, entitled Systems and Methods for Terrestrial Reuse of Cellular Satellite Frequency Spectrum; and Published U.S. Patent Application Nos. U.S. 2003/0054760 to Karabinis, entitled Systems and Methods for Terrestrial Reuse of Cellular Satellite Frequency Spectrum; U.S. 2003/0054761 to Karabinis, entitled Spatial Guardbands for Terrestrial Reuse of Satellite Frequencies; U.S. 2003/0054814 to Karabinis et al., entitled Systems and Methods for Monitoring Terrestrially Reused Satellite Frequencies to Reduce Potential Interference; U.S. 2003/0073436 to Karabinis et al., entitled Additional Systems and Methods for Monitoring Terrestrially Reused Satellite Frequencies to Reduce Potential Interference; U.S. 2003/0054762 to Karabinis, entitled Multi-Band/Multi-Mode Satellite Radiotelephone Communications Systems and Methods; U.S. 2003/0153267 to Karabinis, entitled Wireless Communications Systems and Methods Using Satellite-Linked Remote Terminal Interface Subsystems; U.S. 2003/0224785 to Karabinis, entitled Systems and Methods for Reducing Satellite Feeder Link Bandwidth/Carriers In Cellular Satellite Systems; U.S. 2002/0041575 to Karabinis et al., entitled Coordinated Satellite-Terrestrial Frequency Reuse; U.S. 2002/0090942 to Karabinis et al., entitled Integrated or Autonomous System and Method of Satellite-Terrestrial Frequency Reuse Using Signal Attenuation and/or Blockage, Dynamic Assignment of Frequencies and/or Hysteresis; U.S. 2003/0068978 to Karabinis et al., entitled Space-Based Network Architectures for Satellite Radiotelephone Systems; U.S. 2003/0143949 to Karabinis, entitled Filters for Combined Radiotelephone/GPS Terminals; U.S. 2003/0153308 to Karabinis, entitled Staggered Sectorization for Terrestrial Reuse of Satellite Frequencies; and U.S. 2003/0054815 to Karabinis, entitled Methods and Systems for Modifying Satellite Antenna Cell Patterns In Response to Terrestrial Reuse of Satellite Frequencies. The disclosures of all of above referenced patents and patent publications are hereby incorporated herein by reference in their entirety as if set forth fully herein.

FIG. 4 is a block diagram illustrating a satellite 101 according to embodiments of the present invention. As shown, the satellite 101 may provide links for transmission/reception between a satellite gateway and a radioterminal using one or more feeder link antenna(s) 401, one or more feeder link receivers 403 a-b, one or more service link transmitter(s) 405, one or more service link antenna(s) 407, one or more service link receiver(s) 411, one or more feeder link transmitters 413 a-b, and a plurality of linear frequency translators FTA1-4 and FTB1-4. More particularly, the feeder link antenna(s) 401 and the feeder link receivers 403 a-b may provide reception of up link portions of feeder links (e.g., Feeder Link 1 and/or Feeder Link 2) from satellite gateways (e.g., 103 a and/or 103 b). The feeder link antenna(s) 401 and the feeder link transmitters 413 a-b may provide transmission of down link portions of feeder links (e.g., Feeder Link 1 and/or Feeder Link 2) to satellite gateways (e.g., 103 a and/or 103 b). The service link antenna(s) 407 and the service link receiver 411 may provide reception of up link portions of service links (e.g., Service Links 1-5) from radioterminals (e.g., 105 a-e) in respective coverage areas (e.g., 107 a-e). The service link antenna(s) 407 and the service link transmitter 411 may provide transmission of down link portions of service links (e.g., Service Links 1-5) to radioterminals (e.g., 105 a-e) in respective coverage areas (e.g., 107 a-e).

A single service link antenna 407 may provide different service links (also referred to as spot beams) for different coverage areas. While the service link antenna(s) 407 is shown as a single block, separate receive and transmit service link antennas may be used, and/or different service link antennas may be used for different service links for different coverage areas. According to some embodiments of the present invention, the service link antenna(s) 407 may include at least one phased array antenna providing a plurality of spot beams with each spot beam supporting a service link for a different coverage area. Accordingly, beam forming techniques according to embodiments of the present invention may be used so that up link and/or down link portions of the service links (Service Links 1-5) may be received and/or transmitted using a single phased array service link antenna 407.

Similarly, a single feeder link antenna 401 may provide different feeder links for different satellite gateways. For example, a single feeder link antenna 401 may provide different feeder links to spatially separated gateways using spot beam forming, and/or different directional feeder link antennas may provide different feeder links to spatially separated gateways. In addition or in an alternative, one or more feeder link antennas 401 may provide different feeder links having different (e.g., orthogonal) polarizations. Accordingly, feeder link capacity may be increased by providing different feeder links to different gateways separated by space and/or polarization over the same feeder link frequency band.

According to some embodiments of the present invention, the feeder link receiver 403 a and the feeder link antenna 401 may receive an up link portion of a first feeder link (Feeder Link 1) transmitted from the satellite gateway to the satellite 101 over a feeder link frequency band. The service link transmitter 405 and the service link antenna 407 may transmit a down link portion of a service link (Service Link 1) from the satellite 101 to at least one radioterminal 105 a in a coverage area 107 a over a service link frequency band. Moreover, the service link and the feeder link frequency bands may be different. In addition, the frequency translator FTA1 may provide linear frequency translation of a frequency segment of the up link portion of the feeder link (Feeder Link 1) from the feeder link frequency band to the service link frequency band to provide a frequency segment for the down link portion of the service link (Service Link 1) for coverage area 107 a. As shown in FIGS. 3 a-c, a frequency segment (Segment 1 of FIG. 3 c) of the feeder link frequency band from an up link portion of the feeder link (Feeder Link 1) may be linearly frequency translated using frequency translator FTA1 to provide a frequency segment (Beam 1 of FIG. 3 a) to be transmitted from service link antenna 407 as a service link (Service Link 1) for coverage area 107 a. Because the frequency translator FTA1 provides linear frequency translation, a bandwidth of frequencies spanned by the frequency segment of the feeder link may be the same as a bandwidth of frequencies spanned by the frequency segment of the service link.

The service link transmitter 405 and the service link antenna 407 may provide a down link portion of a second service link (Service Link 2) from the satellite 101 to at least one radioterminal 105 b in a coverage area 107 b over the service link frequency band. The frequency translator FTA2 may provide linear frequency translation of a second frequency segment of the up link portion of the feeder link (Feeder Link 1) from the feeder link frequency band to the service link frequency band to provide a frequency segment for the down link portion of the service link (Service Link 2) for coverage area 107 b. As shown in FIGS. 3 a-c, a frequency segment (Segment 2 of FIG. 3 c) of the feeder link frequency band from an up link portion of the feeder link (Feeder Link 1) may be linearly frequency translated using frequency translator FTA2 to provide a frequency segment (Beam 2 of FIG. 3 b) to be transmitted from service link antenna 407 as a down link portion of a second service link (Service Link 2) for coverage area 107 b.

The frequency translators FTA1 and FTA2 may thus translate different non-overlapping frequency segments of the up link portion of the same feeder link to the service link frequency band to provide down link portions of different service links for different coverage areas. More particularly, the first frequency segment (Beam 1 of FIG. 3 a) may provide content for a first plurality of radioterminals (including radioterminal 105 a) in the first coverage area 107 a, and the second frequency segment (Beam 2 of FIG. 3 b) may provide content for a second plurality of radioterminals (including radioterminal 107 b) in the second coverage area 107 b. The feeder link receiver 403 a may thus be configured to receive an up link portion of a single feeder link (Feeder Link 1) from a single satellite gateway 103 a, and different frequency segments of the up link portion of the single feeder link may be translated from the feeder link frequency band to the service link frequency band using respective linear frequency translators FTA1 and FTA2.

In addition, the feeder link receiver 403 b and the feeder link antenna 401 may receive an up link portion of a second feeder link (Feeder Link 2) between from a second satellite gateway 103 b over a feeder link frequency band. The service link transmitter 405 and the service link antenna 407 may transmit a down link portion of a third service link (Service Link 3) from the satellite 101 to at least one radioterminal 105 d in a coverage area 107 d over a service link frequency band. As discussed above, the service link and the feeder link frequency bands may be different. In addition, the frequency translator FTA3 may provide linear frequency translation of a frequency segment of the up link portion of the second feeder link (Feeder Link 2) from the feeder link frequency band to the service link frequency band to provide a frequency segment of the down link portion of the third service link (Service Link 3) for coverage area 107 d. A frequency segment of the feeder link frequency band from an up link portion of the feeder link (Feeder Link 2) may be linearly frequency translated using frequency translator FTA3 to provide a frequency segment (for a spot beam) to be transmitted from service link antenna 407 as a down link portion of a service link (Service Link 3) for coverage area 107 d. Because the frequency translator FTA3 provides linear frequency translation, a bandwidth of frequencies spanned by the frequency segment of the up link portion of the feeder link may be the same as a bandwidth of frequencies spanned by the frequency segment of the down link portion of the service link.

The service link transmitter 405 and the service link antenna 407 may transmit a down link portion of a fourth service link (Service Link 4) from the satellite 101 to at least one radioterminal 105 c in a coverage area 107 c over the service link frequency band. The frequency translator FTA4 may provide linear frequency translation of a fourth frequency segment of the up link portion of the second feeder link (Feeder Link 2) from the feeder link frequency band to the service link frequency band to provide a frequency segment of the down link portion of the fourth service link (Service Link 4) for coverage area 107 c. A frequency segment of the feeder link frequency band from an up link portion of the second feeder link (Feeder Link 2) may be linearly frequency translated using frequency translator FTA4 to provide a frequency segment (for a spot beam) to be transmitted from service link antenna 407 as a down link portion of a fourth service link (Service Link 4) for coverage area 107 c.

The frequency translators FTA3 and FTA4 may thus translate different non-overlapping frequency segments of the up link portion of the same feeder link to the service link frequency band to provide down link portions of different service links for different coverage areas. More particularly, the third frequency segment may provide content for a third plurality of radioterminals (including radioterminal 105 d) in the third coverage area 107 d, and the fourth frequency segment may provide content for a fourth plurality of radioterminals (including radioterminal 105 c) in the second coverage area 107 c. The feeder link receiver 403 b may thus be configured to receive an up link portion of a single feeder link (Feeder Link 2) from a single satellite gateway 103 b, and different frequency segments of the up link portion of the single feeder link may be translated from the feeder link frequency band to the service link frequency band using respective linear frequency translators FTA3 and FTA4.

The up link portions of the first and second feeder links (Feeder Link 1 and Feeder Link 2) may operate over the same feeder link frequency band to increase feeder link capacity. Accordingly, separation between the feeder links may be provided using spatial separation of the satellite gateways and/or using different polarizations. For example, the satellite gateways 103 a-b may be sufficiently separated in geography that up link portions of the different feeder links may be received at the satellite 101 using different directional receive antennas and/or using a receive antenna array capable of receiving different feeder link spot beams. In addition or in an alternative, the satellite gateways 103 a-b may transmit using different (e.g. orthogonal) polarizations, and the feeder link antenna 401 and/or the feeder link receivers 403 a-b may be able to separate up link portions of the different feeder links having the different polarizations.

Moreover, a priori known pilot signals may be used by the satellite 101 to reduce interference between up link portions of the two feeder link signals. For example, first pilot signals may be transmitted from the first satellite gateway 103 a to the satellite 101 over the up link portion of the first feeder link (Feeder Link 1), and second pilot signals may be transmitted from the second satellite gateway 103 b to the satellite 101 over the up link portion of the second feeder link (Feeder Link 2) with the first and second pilot signals being different. The feeder link receivers 403 a and/or 403 b may then perform interference cancellation based on a priori knowledge of the first and second pilot signals.

According to additional embodiments of the present invention, the feeder link transmitter 413 a and the feeder link antenna 401 may transmit a down link portion of a first feeder link (Feeder Link 1) from the satellite 101 to the satellite gateway 103 a over a feeder link frequency band. The service link receiver 411 and the service link antenna 407 may receive an up link portion of a service link (Service Link 1) from at least one radioterminal 105 a in a coverage area 107 a over a service link frequency band. Moreover, the service link and the feeder link frequency bands may be different. In addition, the frequency translator FTB1 may provide linear frequency translation of a frequency segment of the up link portion of the service link (Service Link 1) from the service link frequency band to the feeder link frequency band to provide a frequency segment for the down link portion of the feeder link (Feeder Link 1) from coverage area 107 a. A frequency segment of the service link frequency band from an up-link portion of the service link (Service Link 1) from coverage area 107 a may be linearly frequency translated using frequency translator FTB1 to provide a frequency segment to be transmitted from the feeder link antenna 401 as a frequency segment of the down link portion of the feeder link (Feeder Link 1) to the satellite gateway 103 a. Because the frequency translator 413 a provides linear frequency translation, a bandwidth of frequencies spanned by the frequency segment of the down link portion of the feeder link may be the same as a bandwidth of frequencies spanned by the frequency segment of the up link portion of the service link.

The service link receiver 411 and the service link antenna 407 may receive an up link portion of a second service link (Service Link 2) from at least one radioterminal 105 b in a coverage area 107 b over the service link frequency band. The frequency translator FTB2 may provide linear frequency translation of a second frequency segment of the up link portion of the second service link (Service Link 2) from the service link frequency band to the feeder link frequency band to provide a second frequency segment for the down link portion of the feeder link (Feeder Link 1) from the coverage area 107 b. The up link portion of the second service link (Service Link 2) for the coverage area 107 b may thus be linearly frequency translated using frequency translator FTB2 to provide a second frequency segment for the down link portion of the feeder link (Feeder Link 1).

The frequency translators FTB1 and FTB2 may thus translate up-link portions of different service links (e.g., Service Link 1 and Service Link 2) to different non-overlapping frequency segments of the down link portion of the same feeder link (e.g., Feeder Link 1) to provide up link portions of service links for different coverage areas. More particularly, a first frequency segment (e.g., an up-link portion) of the first service link (Service Link 1) may provide content from a first plurality of radioterminals (including radioterminal 105 a) in the first coverage area 107 a, and the second frequency segment (e.g., an up-link portion) of the second service link (Service Link 2) may provide content from a second plurality of radioterminals (including radioterminal 105 a) in the first coverage area 107 a. The feeder link transmitter 413 a may thus be configured to transmit a down link portion of a single feeder link (Feeder Link 1) to a single satellite gateway 103 a, and different frequency segments of the down link portion of the single feeder link may be translated to the feeder link frequency band from the service link frequency band using respective frequency translators FTB1 and FTB2.

In addition, the feeder link transmitter 413 b and the feeder link antenna 401 may provide transmissions over a down link portion of a second feeder link (Feeder Link 2) from the satellite 101 to the satellite gateway 103 b over the feeder link frequency band. The service link receiver 411 and the service link antenna 407 may receive an up link portion of a third service link (Service Link 3) from at least one radioterminal 105 d in coverage area 107 d over the service link frequency band. As discussed above, the service link frequency band and the feeder link frequency band may be different. In addition, the frequency translator FTB3 may provide linear frequency translation of a frequency segment of the up link portion of the third service link (Service Link 3) for coverage area 107 d from the service link frequency band to the feeder link frequency band to provide a third frequency segment for the down link portion of the second feeder link (Feeder Link 2). Because the frequency translator FTB3 provides linear frequency translation, a bandwidth of frequencies spanned by the frequency segment for the down link portion of the feeder link may be may be the same as a bandwidth of frequencies spanned by the frequency segment for the up link portion of the service link.

The service link receiver 411 and the service link antenna 407 may also receive an up link portion of a fourth service link (Service Link 4) from at least one radioterminal 105 c in a coverage area 107 c over the service link frequency band. The frequency translator FTB4 may provide linear frequency translation of a fourth frequency segment of the up link portion of the fourth service link (Service Link 4) for coverage area 107 c from the service link frequency band to the feeder link frequency band to provide a fourth frequency segment for the down link portion of the second feeder link (Feeder Link 2). A frequency segment of the service link frequency band from an up link portion of the fourth service link (Service Link 4) may be linearly frequency translated using frequency translator FTB4 to provide a frequency segment to be transmitted from the feeder link antenna 401 as a fourth frequency segment for the down link portion of the second feeder link (Feeder Link 2).

The frequency translators FTB3 and FTB4 may thus translate up link portions of different service links (e.g., Service Link 3 and Service Link 4) for different coverage areas (e.g., 107 d and 107 c) from the service link frequency band to different non-overlapping frequency segments of the feeder link frequency band for a down link portion of the same feeder link (e.g., Feeder Link 2). More particularly, the third frequency segment from the up link portion of the third service link (Service Link 3) may provide content from a third plurality of radioterminals (including radioterminal 105 d) in the third coverage area 107 d, and the fourth frequency segment from the up link portion of the fourth service link (Service Link 4) may provide content from a fourth plurality of radioterminals (including radioterminal 105 c) in the fourth coverage area 107 c. The feeder link transmitter 413 b may thus be configured to transmit a down link portion of a single feeder link (Feeder Link 2) to a single satellite gateway 103 b, and different frequency segments of the down link portion of the single feeder link may be translated from the service link frequency band to the feeder link frequency band using respective linear frequency translators FTA3 and FTA4.

The down link portions of the first and second feeder links (Feeder Link 1 and Feeder Link 2) transmitted using the feeder link transmitters 413 a and 413 b may operate over the same feeder link frequency band to increase feeder link capacity. Accordingly, separation between the feeder links may be provided using directional spot beams, using spatial separation of the satellite gateways, and/or using different polarizations. For example, the satellite gateways 103 a-b may be sufficiently separated in geography that the different down link portions of the feeder links may be transmitted from the satellite 101 using different directional transmit antennas and/or using a transmit antenna array capable of transmitting different feeder link spot beams. In addition or in an alternative, the satellite gateways 103 a-b may selectively receive different (e.g., orthogonal) polarizations, and the feeder link antenna 401 and/or the feeder link transmitters 413 a-b may be configured to transmit the down link portions of the different feeder links using different polarizations.

Moreover, a priori signals may be used by the satellite gateways 103 a and/or 103 b to reduce interference between down link portions of the two feeder link signals. For example, first pilot signals may be transmitted from the first feeder link transmitter 413 a and/or the feeder link antenna 401 to the satellite gateway 103 a over the down link portion of the first feeder link (Feeder Link 1), and second pilot signals may be transmitted from the second feeder link transmitter 413 b and/or the feeder link antenna 401 to the satellite gateway 103 b over the down link portion of the second feeder link (Feeder Link 2), with the first and second pilot signals being different. The satellite gateways 103 a and/or 103 b may then perform interference cancellation based on a priori knowledge of the first and second pilot signals.

In the drawings and specification, there have been disclosed embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. The following claims are provided to ensure that the present application meets all statutory requirements as a priority application in all jurisdictions and shall not be construed as setting forth the scope of the present invention. Moreover, while particular systems are discussed above with respect to the figures, analogous methods are also included in the present invention.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4450582Sep 14, 1981May 22, 1984Vitalink Communications CorporationMethod and apparatus for increasing the capacity of a satellite transponder by reuse of bandwidth
US4901307Oct 17, 1986Feb 13, 1990Qualcomm, Inc.Spread spectrum multiple access communication system using satellite or terrestrial repeaters
US4965809 *Jun 28, 1989Oct 23, 1990Nec CorporationUplink cross-polarization interference canceller using correlation calculator and stepwise tracking controller
US5073900Mar 19, 1990Dec 17, 1991Mallinckrodt Albert JIntegrated cellular communications system
US5303286Mar 29, 1991Apr 12, 1994Space Systems/Loral, Inc.Wireless telephone/satellite roaming system
US5339330Oct 24, 1991Aug 16, 1994David D. OttenIntegrated cellular communications system
US5394561Jul 22, 1993Feb 28, 1995Motorola, Inc.Networked satellite and terrestrial cellular radiotelephone systems
US5446756Oct 28, 1993Aug 29, 1995Celsat America, Inc.Integrated cellular communications system
US5448623Mar 20, 1995Sep 5, 1995Space Systems/Loral, Inc.Satellite telecommunications system using network coordinating gateways operative with a terrestrial communication system
US5511233Apr 5, 1994Apr 23, 1996Celsat America, Inc.System and method for mobile communications in coexistence with established communications systems
US5555257May 16, 1995Sep 10, 1996Ericsson Ge Mobile Communications Inc.Cellular/satellite communications system with improved frequency re-use
US5584046Nov 4, 1994Dec 10, 1996Cornell Research Foundation, Inc.Method and apparatus for spectrum sharing between satellite and terrestrial communication services using temporal and spatial synchronization
US5612703May 19, 1995Mar 18, 1997Celsat America, Inc.position determination in an integrated cellular communications system
US5619525Jun 6, 1995Apr 8, 1997Globalstar L.P.Closed loop power control for low earth orbit satellite communications system
US5631898May 16, 1995May 20, 1997Ericsson Inc.For transmitting signals to a remote unit
US5761605Oct 11, 1996Jun 2, 1998Northpoint Technology, Ltd.Apparatus and method for reusing satellite broadcast spectrum for terrestrially broadcast signals
US5765098Jul 8, 1996Jun 9, 1998Agence Spatiale EuropeenneMethod and system for transmitting radio signals between a fixed terrestrial station and user mobile terminals via a network of satellites
US5812947Dec 2, 1996Sep 22, 1998Ericsson Inc.Cellular/satellite communications systems with improved frequency re-use
US5832379Oct 6, 1997Nov 3, 1998Celsat America, Inc.Communications system including control means for designating communication between space nodes and surface nodes
US5835857Nov 18, 1996Nov 10, 1998Celsat America, Inc.Position determination for reducing unauthorized use of a communication system
US5848060Aug 21, 1995Dec 8, 1998Ericsson Inc.Cellular/satellite communications system with improved frequency re-use
US5852721Feb 7, 1997Dec 22, 1998Hughes Electronics CorporationMethod and apparatus for selectively retrieving information from a source computer using a terrestrial or satellite interface
US5878329Jan 8, 1997Mar 2, 1999Celsat America, Inc.Power control of an integrated cellular communications system
US5884142Apr 15, 1997Mar 16, 1999Globalstar L.P.Low earth orbit distributed gateway communication system
US5907541Oct 20, 1997May 25, 1999Lockheed Martin Corp.Architecture for an integrated mobile and fixed telecommunications system including a spacecraft
US5926758Aug 26, 1996Jul 20, 1999Leo One Ip, L.L.C.Radio frequency sharing methods for satellite systems
US5937332Mar 21, 1997Aug 10, 1999Ericsson, Inc.Satellite telecommunications repeaters and retransmission methods
US5940753Oct 6, 1997Aug 17, 1999Celsat America, Inc.Controller for cellular communications system
US5991345Sep 22, 1995Nov 23, 1999Qualcomm IncorporatedMethod and apparatus for diversity enhancement using pseudo-multipath signals
US5995832Oct 28, 1998Nov 30, 1999Celsat America, Inc.Communications system
US6011951Aug 22, 1997Jan 4, 2000Teledesic LlcTechnique for sharing radio frequency spectrum in multiple satellite communication systems
US6023605Sep 8, 1997Feb 8, 2000Fujitsu LimitedDual layer satellite communications system and geostationary satellite therefor
US6052560Oct 15, 1997Apr 18, 2000Ericsson IncSatellite system utilizing a plurality of air interface standards and method employing same
US6052586Aug 29, 1997Apr 18, 2000Ericsson Inc.Fixed and mobile satellite radiotelephone systems and methods with capacity sharing
US6067442Mar 18, 1997May 23, 2000Globalstar L.P.Satellite communications system having distributed user assignment and resource assignment with terrestrial gateways
US6072430Apr 6, 1998Jun 6, 2000Ico Services Ltd.Satellite terminal position determination
US6085094Aug 27, 1998Jul 4, 2000Nortel Networks CorporationMethod for optimizing spectral re-use
US6091933Jan 3, 1997Jul 18, 2000Globalstar L.P.Multiple satellite system power allocation by communication link optimization
US6097752Apr 4, 1997Aug 1, 2000Globalstar L.P.Closed loop power control for low earth orbit satellite communications system
US6101385Oct 9, 1997Aug 8, 2000Globalstar L.P.Satellite communication service with non-congruent sub-beam coverage
US6108561Mar 1, 1999Aug 22, 2000Celsat America, Inc.Power control of an integrated cellular communications system
US6134437Jun 13, 1997Oct 17, 2000Ericsson Inc.Dual-mode satellite/cellular phone architecture with physically separable mode
US6157811Feb 16, 1996Dec 5, 2000Ericsson Inc.Cellular/satellite communications system with improved frequency re-use
US6157834Dec 29, 1997Dec 5, 2000Motorola, Inc.Terrestrial and satellite cellular network interoperability
US6160994Jun 4, 1998Dec 12, 2000Globalstar L.P.Interactive fixed and mobile satellite network
US6169878Dec 16, 1997Jan 2, 2001Northpoint Technology, Ltd.Apparatus and method for transmitting terrestrial signals on a common frequency with satellite transmissions
US6198730Oct 13, 1998Mar 6, 2001Motorola, Inc.Systems and method for use in a dual mode satellite communications system
US6198921Nov 16, 1998Mar 6, 2001Emil YoussefzadehMethod and system for providing rural subscriber telephony service using an integrated satellite/cell system
US6201967Sep 9, 1997Mar 13, 2001Ico Services LtdCommunications apparatus and method
US6233463Feb 9, 1998May 15, 2001Globalstar L.P.Automatic satellite terrestrial mobile terminal roaming system and method
US6240124Nov 2, 1999May 29, 2001Globalstar L.P.Closed loop power control for low earth orbit satellite communications system
US6253080Jul 8, 1999Jun 26, 2001Globalstar L.P.Low earth orbit distributed gateway communication system
US6256497Mar 24, 1998Jul 3, 2001Ico Services LtdInterworking between telecommunications networks
US6324405Sep 9, 1997Nov 27, 2001Ico Services Ltd.Communications apparatus and method for mobile platforms having a plurality of users
US6339707Sep 14, 1999Jan 15, 2002Hughes Electronics CorporationMethod and system for providing wideband communications to mobile users in a satellite-based network
US6404775 *Nov 21, 1997Jun 11, 2002Allen Telecom Inc.Band-changing repeater with protocol or format conversion
US6418147Jan 21, 1998Jul 9, 2002Globalstar LpMultiple vocoder mobile satellite telephone system
US6449461Jul 15, 1996Sep 10, 2002Celsat America, Inc.System for mobile communications in coexistence with communication systems having priority
US6522865Aug 10, 1999Feb 18, 2003David D. OttenHybrid satellite communications system
US6628919Aug 9, 2000Sep 30, 2003Hughes Electronics CorporationLow-cost multi-mission broadband communications payload
US6684057Feb 12, 2002Jan 27, 2004Mobile Satellite Ventures, LpSystems and methods for terrestrial reuse of cellular satellite frequency spectrum
US6735437Jun 26, 1998May 11, 2004Hughes Electronics CorporationCommunication system employing reuse of satellite spectrum for terrestrial communication
US6775251Sep 17, 1998Aug 10, 2004Globalstar L.P.Satellite communication system providing multi-gateway diversity and improved satellite loading
US6785543Jan 29, 2003Aug 31, 2004Mobile Satellite Ventures, LpFilters for combined radiotelephone/GPS terminals
US6856787May 20, 2002Feb 15, 2005Mobile Satellite Ventures, LpWireless communications systems and methods using satellite-linked remote terminal interface subsystems
US6859652Dec 4, 2001Feb 22, 2005Mobile Satellite Ventures, LpIntegrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis
US6879829Apr 20, 2004Apr 12, 2005Mobile Satellite Ventures, LpSystems and methods for handover between space based and terrestrial radioterminal communications, and for monitoring terrestrially reused satellite frequencies at a radioterminal to reduce potential interference
US6892068Aug 1, 2001May 10, 2005Mobile Satellite Ventures, LpCoordinated satellite-terrestrial frequency reuse
US6937857Dec 23, 2002Aug 30, 2005Mobile Satellite Ventures, LpSystems and methods for reducing satellite feeder link bandwidth/carriers in cellular satellite systems
US6975837Jan 21, 2003Dec 13, 2005The Directv Group, Inc.Method and apparatus for reducing interference between terrestrially-based and space-based broadcast systems
US6999720Jun 26, 2002Feb 14, 2006Atc Technologies, LlcSpatial guardbands for terrestrial reuse of satellite frequencies
US7006789Aug 22, 2002Feb 28, 2006Atc Technologies, LlcSpace-based network architectures for satellite radiotelephone systems
US7167528 *Jun 11, 2002Jan 23, 2007General Instrument CorporationModulation system for modulating data onto a carrier signal with offsets to compensate for doppler effect and allow a frequency synthesizing system to make steps equal to channel bandwidth
US20020122408Feb 23, 2001Sep 5, 2002Mullins Dennis RSatellite communications with satellite routing according to channels assignment signals
US20020146979Apr 16, 2001Oct 10, 2002Regulinski Paul LucianCommunications apparatus and method
US20020177465May 3, 2002Nov 28, 2002Robinett Robert L.Multi-mode satellite and terrestrial communication device
US20030003815Dec 20, 2000Jan 2, 2003Yoshiko YamadaCommunication satellite/land circuits selection communications system
US20030022625Sep 17, 2002Jan 30, 2003Otten David D.Hybrid satellite communications system
US20030050008 *Mar 29, 2002Mar 13, 2003Teledesic Llc.Scalable satellite data communication system that provides incremental global broadband service using earth-fixed cells
US20030054761Jun 26, 2002Mar 20, 2003Karabinis Peter D.Spatial guardbands for terrestrial reuse of satellite frequencies
US20030054762Aug 22, 2002Mar 20, 2003Karabinis Peter D.Multi-band/multi-mode satellite radiotelephone communications systems and methods
US20030054814May 28, 2002Mar 20, 2003Karabinis Peter D.Systems and methods for monitoring terrestrially reused satellite frequencies to reduce potential interference
US20030054815Aug 22, 2002Mar 20, 2003Karabinis Peter D.Methods and systems for modifying satellite antenna cell patterns in response to terrestrial reuse of satellite frequencies
US20030068978Aug 22, 2002Apr 10, 2003Karabinis Peter D.Space-based network architectures for satellite radiotelephone systems
US20030073436Aug 22, 2002Apr 17, 2003Karabinis Peter D.Additional systems and methods for monitoring terrestrially reused satellite frequencies to reduce potential interference
US20030149986Feb 25, 2003Aug 7, 2003Mayfield William W.Security system for defeating satellite television piracy
US20030153308Jan 29, 2003Aug 14, 2003Karabinis Peter D.Staggered sectorization for terrestrial reuse of satellite frequencies
US20030224785Dec 23, 2002Dec 4, 2003Karabinis Peter D.Systems and methods for reducing satellite feeder link bandwidth/carriers in cellular satellite systems
US20040072539Jun 18, 2003Apr 15, 2004Monte Paul A.Resource allocation to terrestrial and satellite services
US20040097192 *Jun 23, 2003May 20, 2004Schiff Leonard N.Satellite-based programmable allocation of bandwidth for forward and return links
US20040102156Nov 26, 2002May 27, 2004Loner Patrick J.Systems and methods for sharing uplink bandwidth among satellites in a common orbital slot
US20040110467 *Nov 19, 2003Jun 10, 2004Hughes Electronics CorporationMethod and apparatus for providing wideband services using medium and low earth orbit satellites
US20040121727Dec 8, 2003Jun 24, 2004Karabinis Peter D.Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode
US20040142660Jan 5, 2004Jul 22, 2004Churan Gary G.Network-assisted global positioning systems, methods and terminals including doppler shift and code phase estimates
US20040192200Mar 8, 2004Sep 30, 2004Karabinis Peter D.Satellite assisted push-to-send radioterminal systems and methods
US20040192293Apr 7, 2004Sep 30, 2004Karabinis Peter D.Aggregate radiated power control for multi-band/multi-mode satellite radiotelephone communications systems and methods
US20040192395Mar 8, 2004Sep 30, 2004Karabinis Peter D.Co-channel wireless communication methods and systems using nonsymmetrical alphabets
US20040203393Mar 13, 2002Oct 14, 2004Xiang ChenSystem and method for offsetting channel spectrum to reduce interference between two communication networks
US20040203742Dec 12, 2002Oct 14, 2004Karabinis Peter D.Systems and methods for increasing capacity and/or quality of service of terrestrial cellular and satellite systems using terrestrial reception of satellite band frequencies
US20040240525May 29, 2003Dec 2, 2004Karabinis Peter D.Wireless communications methods and apparatus using licensed-use system protocols with unlicensed-use access points
US20050026606Jun 28, 2004Feb 3, 2005Karabinis Peter D.Systems and methods for modifying antenna radiation patterns of peripheral base stations of a terrestrial network to allow reduced interference
US20050037749Jul 14, 2004Feb 17, 2005Karabinis Peter D.Intra-and/or inter-system interference reducing systems and methods for satellite communications systems
US20050041619Aug 9, 2004Feb 24, 2005Karabinis Peter D.Wireless systems, methods and devices employing forward- and/or return-link carriers having different numbers of sub-band carriers
US20050064813Sep 2, 2004Mar 24, 2005Karabinis Peter D.Systems and methods for inter-system sharing of satellite communications frequencies within a common footprint
US20050079816Oct 14, 2004Apr 14, 2005Karabinis Peter D.Integrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis
US20060003699 *Sep 1, 2005Jan 5, 2006Gibson R NManaging searcher and tracker resources in a wireless communication device
Non-Patent Citations
Reference
1Ayyagari et al., "A satellite-augmented cellular network concept", Wireless Networks, Vo. 4, 1998, pp. 189-198.
2Global.com, "Globalstar Demonstrates World's First Prototype of Terrestrial System to Supplemental Satellite Phones," http://www.globalcomsatphone.com/globalcom/globalstar-terrestrial-system.html, Jul. 18, 2002, 2 pages.
3Global.com, "Globalstar Demonstrates World's First Prototype of Terrestrial System to Supplemental Satellite Phones," http://www.globalcomsatphone.com/globalcom/globalstar—terrestrial—system.html, Jul. 18, 2002, 2 pages.
4International Search Report and Written Opinion of the International Search Report for PCT/US2005/022596.
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US8254832 *Mar 18, 2009Aug 28, 2012Viasat, Inc.Frequency re-use for service and gateway beams
US8494443Nov 18, 2004Jul 23, 2013Comtech Mobile Datacom CorporationLow-cost satellite communication system
US8538323 *Mar 18, 2009Sep 17, 2013Viasat, Inc.Satellite architecture
US8548107Jan 25, 2010Oct 1, 2013Comtech Mobile Datacom CorporationAdvanced multi-user detector
US8548377 *May 30, 2012Oct 1, 2013Viasat, Inc.Frequency re-use for service and gateway beams
US8593339Sep 1, 2009Nov 26, 2013Comtech Mobile Datacom CorporationMobile satellite communications
US8594153Apr 24, 2007Nov 26, 2013Comtech Mobile Datacom CorporationSpread-spectrum receiver with progressive fourier transform
US8670707Mar 16, 2012Mar 11, 2014Orbcomm Sens, LlcLow-cost satellite communication system
US8675711 *Sep 24, 2010Mar 18, 2014Comtech Mobile Datacom CorporationSystem and methods for dynamic spread spectrum usage
US20090291633 *Mar 18, 2009Nov 26, 2009Viasat, Inc.Frequency re-use for service and gateway beams
US20090298416 *Mar 18, 2009Dec 3, 2009Viasat, Inc.Satellite Architecture
US20120244798 *May 30, 2012Sep 27, 2012Viasat, Inc.Frequency re-use for service and gateway beams
US20120276840 *Mar 18, 2009Nov 1, 2012Viasat, Inc.Satellite Architecture
US20120289225 *May 3, 2012Nov 15, 2012Viasat, Inc.Gateway rollout
US20140045421 *Oct 15, 2013Feb 13, 2014Viasat, Inc.Capacity maximization for a unicast spot beam satellite system
Classifications
U.S. Classification455/13.3, 455/428, 455/427, 455/455, 370/316
International ClassificationH04B7/185, H04B7/204
Cooperative ClassificationH04B7/18539, H04B7/2041
European ClassificationH04B7/185M6, H04B7/204B
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